Category Archives: Home Made Monitor

The Raspberry Pi and other small single board computers have really taken off in the past few years, especially with the burgeoning wave of development, both commercial, but mainly hobbyist of the Internet of Things (IoT) arena.

Now Raspberry Pi (I am focusing on RPi here because it kicked off the whole shebang in a big way, small SBC’s existed before then but they were not as widely available or used) was never intended to be a IoT board, it was originally intended to be used to teach programming to children. The success of this original project (with over 5 million, yes that is 5,000,000 sold) has not only spawned a myriad of projects but a whole bunch of clones and similar devices looking to capitalize on the success of the project.

With the hobbyist community getting a hold of these devices and putting them into various projects one has to question the cost of these devices. The devices for those who do not know cost US$25 or US$35 depending on the board revision however you also need to add a SD card (either standard or micro depending on revision), power supply, case (enclosure) and if needed a USB wireless dongle and you are looking at getting towards US$100, not as cheap as it sounds to be, and that’s in a basic headless configuration.

The other side to this is the environmental cost, with all these devices (remember there are 5 million RPi’s alone) floating around that will at some point in there lives end up being thrown out, and mostly into landfill it is not overly environmentally cost effective with all those electronics leaching chemicals and other materials over time. What causes this, upgrades to newer models or migrations to other platforms, or even loss of interest, the result is the same.

Now don’t get me wrong, I am not saying these systems are all wasted, or all an issue. Many interesting projects and products are developed from them, not to mention the education that people get from developing on and for these systems. What I am saying is that their use should be more specialized to where the processing power is actually required or used to aggregate the data (done through a technology such as MQTT), cache it and forward it to a more powerful management system (home server anyone).

Further to this, the idea here merges nicely with my move to containers (Docker) and my continuing work with Virtual Machines. If we take the services the RPi runs for each function and put them into a container, and that container syncing through either MQTT or directly through the applications services to a micro controller which then carries out the functions.

Why is this more efficient, because the micro controller only needs to be dumb, it needs to either read the data on the interface and report it to the server, or turn an interface on or off (or perhaps “write” a PWM value) to perform a function. This micro controller does not need to be replaced or changed when changing or upgrading the server, and can even be re-tasked to do something else without reprogramming the controller and only changing the functions and code on the mother controller node.

Much more efficient and effective. It does however have the downfall of an extra failure point so some simple smarts on the micro controller would be a good idea to allow it to function without the mother controller in the event of a failure but the MQTT controls are agnostic so we can work with that, at least for monitoring.

Yes, yes I know I should finish other projects first, but I have yet another electronics project I want to start playing with, and this post is more for a reminder of what it was I was aiming to achieve more than anything else.

As I have been falling more and more down the self sufficient/home made produce rabbit hole, I have noticed that I need more and more data for certain things, so that I can then act upon it, or even better yet, have an automated system to act apon it for me.

The two things I am thinking of, are specifically the (dry) curing of meats such as salami’s and the aging of cheese. Both these are reliant on maintaining the right temperature and humidity within a certain range for a prolonged period of time, ranging from weeks to years depending on what your wanting to achieve. Now in the past this has been what I have been designing SafeDuino to do, and whilst that does other things in addition to monitoring temperature and humidity, some of those more advanced are not needed by the monitoring and control software.

Whilst it may be more benficial to “recycle” code from the SafeDuino project. I am finding myself drawn more and more to the Particle Photon system for these basic requirements as not only as it generally cheaper than the Arduino’s (Freetronics EtherTen and EtherMega) I have been using, but it does come with built in WiFi. Conversly I then have to supply power to the device, either through a paraciticle connection to something else, a dedicated connection to it, or a Solar/Wind & Battery solution, where as the EtherTen and EtherMega boards (with the use of a PoE module) can pull power from the PoE switching equipment I have in the house. A wired connection is always going to be more reliable and faster anyway, although the speed is irrelevent when your doing so little data transfer. Using wireless also means I need to ensure that I have wireless access at each point on the property where I want a monitor, which is easier said that done when we have a large property, much larger than any one or two wireless points can handle, although this is due mainly to the construction materials of the buildings on the property and the distances involved.

This leaves me wondering how to achieve this. Given the design of what I want to achieve, being able to control one or more chambers, through one or more devices I am thinking I need to build it as to make extensive use of 1 wire and I2C technologies, ideally linking back to a Paricle Photon (it has considerably more processing power than an Arduino) and then back to a server. Simular to what they have done with BrewPi, but this means as I said above power supply issues to due no PoE connector, and connectivity issues…

Anyway I will think on it further, but I will most likely end up using the Particle Photon.

What I need to achieve however is rather simple, as I said above monitoring one or multiple “cambers” from a single root node (the Particle Photon) and reporting the data back to a server, where it can be further processed and acted upon if need be. These “chambers” can be joined, or independent, and may or may not have one or more common components (think combo fridge/freezer where the compressor is common to both).

Each “chamber” must be capable of having unique settings (within reason, you cannot expect it to keep one chamber at 30 degrees Celcius and the other at 10, its just not going to happen if you have common components) and be able to work out how to handle this.

I guess it is time to start designing (and finishing off other projects)